It seems like it would be pretty easy to make the ID's. The first thing you would need is a printer that has a CD/DVD printer tray. The Canon PIXMA MG7520, available here on Amazon for $200 would probably do. Then, you need an ID tray, one that will work with the printer, but replace the CD/DVD tray. That specific printer uses a type of tray referred to as 'Tray J'. You can buy an ID tray for Tray J type on this great site, brainstormidsupply.com. You can also buy Inkjet PVC cards there for relatively cheap. Finally, you need a template to print to. Using Photoshop, in Print Settings, you can choose Printable disc under media type, and Disc tray J under Printer Paper Size. Then, use a template for Tray J. I couldn't find one online, so I made one that's downloadable here for novelty purposes.
After that, it's pretty straightforward. However this would not create a fully operational ID yet though, as a few things are missing. For one, I was wrong when I said it worked off of 13.56 MHz RFID tech. It does work off of 125 kHz, but it uses HID, which means the reader I got doesn't work with it. I haven't put much effort into making a 125 kHz spoofer, though there are some rough instructions that I found here for a universal 125 kHz RFID key. You can also buy one for roughly $300, but that's a bit out of my price range.
Another interesting thing is that the true DiD's have UV ink on them. On the edges of the cards there's a thin line that only shows up under UV light. I'm not sure if that's a byproduct of the printing process or if it's intended, but in any case I don't think anyone else knows that it exists.